Do you have GOTY edition? Or did you pick up the disks separately?
If you have GOTY, install Oblivion, and then SI. SI patches the game to the latest and greatest. (1.2.0416) Then install the rest of the DLC. (don't worry about additional patches, you don't need them.)
If you DON'T have GOTY.... Install Oblivion, SI, and the SI patch according to what version of the game you have. (north american, UK english, etc.) Then whatever DLC you happen to have. With just those installed, see if behavior changes any. (patches are available from http://www.elderscrolls.com/downloads/updates_patches.htm...
I have seperate disks, got them off a carboot because i'm a cheapo and don't want to pay full price on steam.
Attempt #1
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Installed Oblivion
Patched Oblivion with V1.2.0416UK
Installed Shivering Isles (With fixed Exe, disk version won't work)
Tried to Patch Shivering Isles with ShiveringIsles V1.2.0416English, wich failed giving me a warning:
'Old File not found. However, a file of the same name was found. No update done since file contents do not match.' thus ceased the attempt.
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Attempt #2
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Installed Oblivion
Installed Shivering Isles (With fixed Exe, disk version won't work)
Installed Shivering Isles Patch (v1.2.0416English)
Tried Patch from the Knights of the Nine Disk (Oblivion v1.1FinalEnglish) as stated on the Instructions, wich failed giving me a warning:
'Old File not found. However, a file of the same name was found. No update done since file contents do not match.'
Installed DLC from the Knights of the Nine Disk in order stated on the instructions.
Result: DeathCrash
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Attempt #3
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Installed Oblivion
Installed Shivering Isles (With fixed Exe, disk version won't work)
Installed Shivering Isles Patch (v1.2.0416English)
Installed DLC from the Knights of the Nine Disk in order stated on the instructions.
Result: DeathCrash
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Attempt #4
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Installed Oblivion, tried to see if it started a game to determin if its an addon causing the crash, however the Deathcrash happens with just Oblivion installed.
Oblivion version 1.0.228